Wagner, who hated Jews to the extent that he actually wrote anti-Semitic screeds, has long been associated with the Nazi regime. He was cited by Hitler as the greatest of all German composers and his music was used in official Nazi propaganda.

But the family’s dark past doesn’t end there. Ms Wagner’s father, Wolfgang Wagner, was a former member of the Hitler Youth as well as a Wehrmacht soldier who ran the Bayreuth festival between 1951 to 2008.

Twelve Jewish musicians who performed at the Wagner festival at Bayreuth were murdered by the Nazis.

Ms Wagner, who is now co-director of the festival with her sister, told Der Tagesspiegal newspaper: “He had a very negative to the Nazi regime and was happy that he was injured as a young man, and therefore got sent back from the front and survived.

“He always said we can be very happy that we lost the war.”

But a well-known historian has accused the Wagner family of not being transparent. Hannes Heer told The Daily Telegraph: “The facts must come out about the negative role of Richard Wagner.

“Then you can approach the great artist Wagner with a clear conscience.”

Katharina Wagner hopes a more transparent approach to her great-grandfather will lead to a rehabilitation of him and his works.

She has also made attempts to mitigate the animosity towards Wagner by Israelis. In October 2010 she sought to end a post-1945 boycott of Wagner’s music in Israel by inviting the Israel Chamber Orchestra to play a concert in July 2011 at the Bayreuth town hall.

Her own visit to Israel was canceled after hostility from Holocaust survivors.